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The results of radiation dose in the air

Mobile site of results
http://www.aist.go.jp/mb/top.php

<Place of Monitoring>  AIST Tsukuba Central 1, Higashi 1-1, Tsukuba, Ibaraki Prefecture

<Measurement Conditions>

-Measuring instrument: Scintillation survey meter TCS-171

-Measurement Result: We deducted the background radiation (0.06µSv/h) from the original results to get the announced results below.

*The data will be updated every one hour.

*The upload of the survey results could be temporarily delayed because of possible system instability.

Date	Time	Result (µSv/h)
		Balcony (3F)
2/3	15:00	0.06
	14:00	0.05
	13:00	0.05
	12:00	0.05
	11:00	0.05
	10:00	0.05
	09:00	0.06
	08:00	0.05
	07:00	0.05
	06:00	0.05
	05:00	0.06
	04:00	0.05
	03:00	0.05
	02:00	0.05
	01:00	0.06
	00:00	0.05
2/2	23:00	0.06
	22:00	0.04
	21:00	0.07
	20:00	0.07
	19:00	0.05
	18:00	0.06
	17:00	0.06
	16:00	0.05

All results of the survey

History
  March 15, 2011 – March 16, 2012 : Manual measurements at the parking lot
  March 17, 2011 – Present : Automatic continuous measurements at the balcony

Distance from the ground, effects of buildings, wind direction, or temperature-dependent characteristics of instruments might cause the differences between the data measured at the two points, the parking lot and the balcony.
As the background radiation data at the balcony is not available, we assume that the background radiation is the same as that at the parking lot (0.06 µSv/h).

Radiation Activity Fallout Measurement

AIST measures energy spectra of the ionizing radiations from fallout using a Germanium semiconductor detector. The fallout sample is obtained by smearing on a vinyl sheet, which is the size of 1 m times 1.5 m and put on the ground at AIST. The following figure shows the energy spectra of the ionizing radiation from the fallout sample (red) and background (blue). We found radionuclides of Te-132, I-131, I-132, I-133, Cs-134, and Cs-137. These radionuclides are expected to be released from the nuclear power plants at Fukushima because these are not exist in the environment.

Photon energy spectra from the fallout sample smeared on the vinyl sheet on the ground at NMIJ measured on March 15, 2011 (red) and March 19, 2011 (green). The blue curve shows the background.

The following data show the change of the radioactivity of these radionuclides.

*AIST stopped the radio activity fallout measurements on April 8. This is due to the facts that the radiation dose in the air measured at AIST Tsukuba is decreasing constantly and that only trace amounts of radionuclides are detected for more than a week.

(1) The sampling area is 1 m x 1.5 m on a vinyl sheet.
(2) The measured values change slightly due to sampling conditions.
(3) The sampling time changes due to rain.

Change of the radioactivity of the detected radionuclides

Germanium semiconductor detector system at NMIJ

Links

• National Institute of Radiological Sciences
• IBARAKI Prefectural Government
• Radiation measurement at NIMS Sengen-site
• The ambient radiation level at KEK
• Radiation Level at the Radioisotope Center�EUniversity of Tsukuba